This invention relates to railway track work and is particularly concerned with a frog for use on high speed railroad track.
High speed railroad traffic (trains traveling at over 100 mph) requires the use of movable frogs which have a continuous tread to support the wheels of passing traffic. Conventional spring rail frogs serve this purpose but in one direction only. That is, they will usually have a continuous tread in the straight through direction but not in the turn out direction. Thus, high speed traffic can travel only in the straight through direction; turn out traffic must pass the frog at a low speed. The present invention is concerned with frogs which allow passage of high speed traffic in either a straight through direction or a turn out direction.
Various arrangements have been tried in attempting to make a frog which handles high speed traffic in two directions. One way is to have fixed wing rails with a movable point between them. One problem with movable point frogs is that plastic deformation in the rail head of the point in the pivot area will eventually prevent it from seating tightly against the wing rails. In order for the moving point frog to work properly, a great deal of maintenance is required. For example, on some railroads it is necessary to inspect and maintain the frogs nightly to insure proper operation.
Another movable frog arrangement has fixed wing rails and movable point rails. To achieve a throw, one of the point rails is straight and mates with a wing rail but the other one must be bent out of the way to form a flangeway. In order to accomplish this the base of the point rails must be removed. This induces stress risers and weakens the rail.